Lithium difluorobis(oxalato)phosphate is used as an additive for nonaqueous electrolyte batteries, such as lithium ion batteries, lithium ion capacitors, etc. Furthermore, as a method for producing lithium difluorobis(oxalato)phosphate, there is known a method of reacting lithium hexafluorophosphate in an organic solvent in the presence of an reaction aid containing SiCl4 (Patent Publication 1). In this method, it is difficult to purify the lithium difluorobis(oxalato)phosphate solution by crystallization. Therefore, it is extremely difficult to obtain a lithium difluorobis(oxalato)phosphate, in which chlorine compounds and free acids are little, which produce an adverse effect on battery characteristics of nonaqueous electrolyte batteries.